The present invention relates to a semiconductor device which is preferably used in, for example, a semiconductor integrated circuit device having a power supply circuit.
A semiconductor integrated circuit device having a power supply circuit is generally provided with a power supply circuit for generating a controlled internal power supply voltage by dropping a power supply voltage (external power supply voltage) supplied from the outside of the semiconductor device. Usually, a power supply circuit includes a drive transistor, a voltage dividing circuit, a reference voltage circuit, and an error amplifier. The drive transistor is coupled between a power supply line which receives the external power supply voltage and a power supply line which supplies the internal power supply voltage. The error amplifier controls a voltage to be applied to a control electrode (gate) of a control transistor in accordance with the difference voltage between a divided voltage of the internal power supply voltage, which is output from the voltage dividing circuit and a reference voltage which is output from the reference voltage circuit.
Patent literature 1 discloses a power supply circuit having a comparison circuit for comparing a reference voltage with an output voltage and a circuit for suppressing, to be within a predetermined range, a fluctuation in the output voltage with respect to a fluctuation in an external supply voltage. The circuit has a transistor which is current-mirror-coupled to a switch MOS (Metal Oxide Semiconductor) transistor for controlling the output voltage in the case where a fluctuation occurs in the external supply voltage, and controls the switch MOS transistor so as to follow the fluctuation in the external supply voltage.